Clinicians are commonly consulted by parents of infants aged 6–24 months about infant sleep disturbance (ISD). Considerable research over the last two decades has contributed to our knowledge of ISD but has failed to lead to a comprehensive aetiological explanation. This research is reviewed and identifies: (i) individual factors associated with sleep disturbance; (ii) interactive mechanisms linking these associated factors; and (iii) the relationship between learning and infant sleep disturbance. The findings of this research are incorporated into models describing proximal factors involved in the three processes considered important in the development of sleep disturbance: (i) the development of sleep self-initiation at around 3 months of age; (ii) the development of primary sleep disturbance by 6 months of age; and (iii) the development of secondary sleep disturbance later in the first or second year. Description of the influence that proximal factors have on sleep disturbance, organized in these three models, is the most appropriate way of presenting this complex material for the clinician. Changing these proximal factors is important in both prevention and management.